What Is Lens Distortion?

Lens distortion can be a big problem in photography. There are two different types of distortion in photography: optical and perspective.

It is important to know which is which. This will help you know how to fix the distortion.
For help in choosing lenses, here is our extensive article that will help you find the perfect set for you.

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Optical Distortion

Every lens has varying degrees of distortion, some more than others. Fisheye and wide-angle lenses have the most as they have a ‘wider’ view.

The distortion definition is simple. It comes from the optical design, or rather, how the lens was made. Optical distortion is down to the lens. This is why we often call it lens distortion.

Perspective distortion happens because of the position of the camera relative to the subject.
Optical lens distortion in photography is also known as an optical aberration. The straight lines in the photograph become bendy and wavy. This is why they are also known as “curvilinear”.

This distortion occurs due to the lens design, which is actually a lens error.

There are two types of optical distortion that we will look at. These are Barrel (Convex) and Pincushion (Concave).
This below image is our base as it has no distortion. This grid image is a great way to define distorted images and distortion photography.

‘Perfect’ lenses or lenses with no picture distortion are rare. Most lenses will suffer from one of these distortions.
Some lenses are made with elements that significantly reduce the aberrations. So much so that they are not noticeable to the naked eye.

Some lenses suffer from both types of distortion mentioned here.
A superzoom or telephoto will give you distortions at different focal lengths. The Sigma 18-300mm f/3.5-6.3 is a good example here.

Barrel Distortion (Convex)

Barrel distortion happens when lines curve towards you like the lines of a barrel. This distortion is very common to wide angle and fisheye lenses.

This is because the field of view from the lens is much bigger than the sensor, so it needs to be ‘squeezed’ in to fit.
This creates curved lines. These become more extenuated towards the edges of the frame. The centre will be straight as the image stays the same but changes the further the distance becomes.

This form of lens distortion effects camera lenses at small focal lengths. Even 50mm prime lenses can yield some distortion at close distances.

Some lenses will have compensating elements, but eliminating the distortion is near impossible. One way or another, you are going to have pincushion or lens barrel distortion.

Lenses house a multitude of these compensating optical elements. This adds to the weight and size of the lens. The Sigma 14-24mm f/2.8 is a good example.

This is why wide-angle lenses are bigger and heavier than standard lenses. They need more elements to remove the wide angle lens distortion.

Fixing this picture distortion is pretty straightforward in Lightroom or other editing software. Each lens is different. And you could benefit from using lens profiles when correcting these aberrations.

Pincushion Distortion (Concave)

Pincushion distortion is the exact opposite of barrel distortion. The lines curve out from the centre. You can find this type of aberration in telephoto lenses. It’s due to increased magnification.

This time, the field of view is smaller than the sensor, so it appears to ‘stretch’ to fit.

As a result, the lines curve towards the centre. They more extenuated towards the edges of the frame. Again, the centre stays the same.

This is a very common aberration, found in zoom lenses. They do have compensating lens elements. These make the picture distortion difficult to spot.

Lenses that have the capacity to go from wide angle to telephoto will suffer from both pincushion and lens barrel distortion. At the widest focal length, you will find barrel distortion.

The smallest will give you pincushion distortion.

Perspective Distortion

The other form of distortion is perspective distortion. Unlike optical distortion, perspective distortion has nothing to do with the lens. It’s not a lens error.

Photographing a 3D subject and turning it into a 2D image causes picture distortion. The subjects become distorted in comparison to the background.

This is because of the closeness to the subject. This distortion extenuates as the distance between the subject and the background grows. And this creates distorted images.

This is a common occurrence and also natural. Our eyes work in the same way. Try bringing an object closer to your eyes. It will make it bigger and distorted compared to the background.

Photographing a portrait up close with a wide-angle lens will distort the person’s nose, eyes and lips.
They will be large compared to the persons’ ears, which might look very small. This is an unnatural look.

The photograph of this man was taken using a wide-angle lens. You can see his chin and lips are much larger than the rest of his face, especially his forehead.
The image will seem smaller due to the focal length and field of view, but the perspective remains the same.
The point of larger focal lengths is that they enlarge the subject in the frame. But keep a normal perspective. Telephoto lenses do not fix the distortion.

They force you to stand further away which changes the perspective.
This image looks very distorted as the banana was very close to the wide-angle lens. The banana looks around half the size of the man in the background, yet in real life, this is absurd.

A normal lens would have kept the sizing like what we would experience in real life. But bringing items closer while keeping others further away still produces distorted images.
One of the best examples of perspective distortion come when we photograph buildings.
This photograph of the Eiffel Tower is a great example of converging lines. The building looks to be leaning away from you.

This is a completely natural distortion as our eyes would see the same thing. It looks like it is leaning, as the top is much farther away than the bottom.

The height of the building extenuates the feeling of it leaning back away from you. Photographers often correct this picture distortion to make the image more appealing.

To find out how to correct lens distortion in a few quick and easy steps using Lightroom, check out our guide here.

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About the Author

Craig is a photographer currently based in Budapest. His favourite photographic areas are street and documentary photography. Show him a darkroom and he'll be happy there for days. As long as there are music and snacks. Find him at craighullphotography.co.uk and Instagram/craighullphoto